Stabilized, cantilevered, patient trauma table system

ABSTRACT

A patient trauma table is described which is adapted for use with medical imaging systems so that the patient can be easily positioned in the imaging system without the necessity of transferring the patient to a special table, making the table extremely useful for supporting a patient during emergency or surgical intervention. The patient trauma table has an elongated top patient-supporting panel capable of being moved into a cantilevered relation to the table base so that a portion of the panel is disposed in an imaging position with respect to the medical imaging equipment. A system for stabilizing the patient supporting panel preferably includes means for releasably locking the table to the imaging equipment to fix the imaging position; and stabilizing support assembly including a support arm having a roller at one end and mounted on the medical imaging equipment so that the roller can be incrementally, vertically moved into and out of contact with the underside of the cantilevered end of the table panel. For safety reasons, a sensor, preferably in the form of a strain gauge, is coupled to the support arm so as to provide an output signal that will stop the advancement of the support arm further against the top when a predetermined roller contact force is exceeded. A counter is provided for counting the steps provided by the stepper motor driving the support arm so that the precise position of the table top with respect to the components of the imaging equipment can be determined.

RELATED APPLICATIONS

This application is related to U.S. patent application Ser. No.08/193,783, filed in the name of Gilbert W. McKenna and entitled "X-rayTomographic Scanning System", now abandoned in favor of copending U.S.patent application Ser. No. 08/359,845 filed Dec. 20, 1994, now U.S.Pat. No. 5,473,657 as a continuation of application Ser. No. 08/193,783,U.S. patent application Ser. No. 08/193,696, now abandoned, filed in thename of Gilbert W. McKenna and Ronald E. Swain and entitled "TomographicScanner Having Center of Rotation for all Physics" (Attorney's DocketNo. ANA-31), now abandoned in favor of copending U.S. patent applicationSer. No. 08/351,880 filed Dec. 8, 1994, now U.S. Pat. No. 5,448,608, asa continuation of application Ser. No. 08/193,696 and U.S. patentapplication Ser. No. 08/193,562, now U.S. Pat. No. 5,448,607 name ofGilbert W. McKenna and entitled "X-ray Tomography System with GantryPivot and Translation Control", all filed simultaneously herewith andassigned to the present assignee.

FIELD OF THE INVENTION

The present invention relates to medical imaging systems, and moreparticularly to an improved, stabilized, cantilevered, patient traumatable for use in such a system.

BACKGROUND, OBJECTS AND SUMMARY OF THE INVENTION

Patient tables, particularly gurneys, are ubiquitous throughouthospitals. Gurneys are well known for transporting patients and usefulfor a variety of specialized tasks. For example, gurneys have been usedto receive traumatized patients in emergency situations, transportpatients from one location to another, as well as serve as operatingtables during surgery. In some cases certain medical imaging equipment,such as ultrasound units can be used on patients lying on gurneyswithout moving the patient, because in such cases the imaging equipmentis readily positionable with respect to the patient.

Larger imaging equipment, such as CT, MRI and PET scan systems, however,are usually too large to move relative to a patient. A CT scan system,for example, includes supporting structure, usually in the form of ayoke, for supporting a gantry. The latter includes a frame, which inturn supports a centrally apertured disk for rotation relative to theframe about a rotation axis. Imaging equipment is mounted on the disk soas to rotate with the disk about its center aperture. The imagingequipment includes an X-ray source which may provide periodic pulses orcontinuous wave radiation. In third generation CT scan machines, X-raysare detected by a detector array mounted on the disk diametricallyacross from the source, while in fourth generation machines X-raysemitted by the source are detected by a plurality of detectors fixedcircumferentially around the frame. In both types of machines thedetectors are positioned and aligned with respect to the source so thatthe ray paths of the X-rays generated by the source and subsequentlysensed by the detectors are all disposed within a common mean scanningplane (perpendicular to the axis of rotation of the disk).

A patient must be positioned through the central aperture of the disk sothat the scanning plane passes through a select part of the patient forwhich an image is to be formed. This arrangement provides informationcorresponding to variations in X-ray absorption measured by thedetectors during rotation of the disk about the patient. Upon known(Radon) mathematical processing of the information, visual images can be"back projected", each representing density distribution of a slicealong the scanning plane, through the part of the patient positioned inthe plane between the source and detectors.

The formation of a meaningful image depends, inter alia, upon thepertinent part of the patient being positioned within the centralaperture of the disk and remaining immobile in that position duringscanning. The quality of the data also critically depends upon (1) theimaging components (i.e., the source, and in the case of thirdgeneration machines also the detectors) positioned on the disk movingthrough a smooth circular path about a common point during a scan, i.e.,the image "center", or "isocenter" (which should be coincident with theaxis of the disk), and (2) the image center remaining fixed relative tothe patient so that no relative, lateral movement occurs between thepatient and the imaging components. Since even minor relative lateralmovement between the patient and the imaging components within thescanning plane during a scan can cause errors resulting in faulty orerroneous images, such apparatus has been provided as massivelyreinforced devices often weighing a ton or more.

MRI and PET equipment exhibits many similar characteristics,particularly being large and heavy because such equipment employs largemagnets. As a result such massive devices are not readily manipulable toadjust the location of the disk aperture to the position of the patient.In addition, since imaging requires the proper positioning of thepatient within the equipment, the table upon which the patient restsmust usually be translated in a direction parallel to the axis of theimaging components. Accordingly, such equipment is typically providedwith its own table coupled to the scanning equipment such that the tablemoves through the center aperture so as to properly position the patientso that the patient can be scanned.

Too often, however, a patient who is in need of a scan is usuallyreposed on a gurney, or other type of patient table, in a traumatizedstate, because, for example, of an injury or because he or she is havingsurgery performed. In such cases it is necessary to transfer the patientfrom the gurney to the table of the scanner which can exacerbate thetrauma and cause harm to the patient. This is particularly a problem insurgery, for example, where a surgeon may want to know whether he or shehas completely removed cancerous tissue, or is entering the brain at aprescribed location. Under such circumstances it would be necessary tosuture the patient to move him or her to the location of a CT scanner,move the patient off the gurney to the scan table, perform the scan,move the patient back to the gurney, and then move the patient back tothe operating room if further surgical intervention is warranted.Because of the possible trauma that can result from such patientmovement during such surgery, such scans are usually not performed.

Accordingly, at least one object of the present invention is to providea patient trauma table, preferably in the form of a gurney, which cansupport a traumatized patient and also function as a table for use withmedical imaging equipment.

Thus, in accordance with one aspect of the present invention, animproved patient table, preferably in the form of a wheel supportedgurney, is provided. The table includes a top panel or palette forsupporting a trauma patient. The top panel is extendable laterallyrelative to a supporting base so that it can extend into the centralaperture of medical imaging equipment such as a CT scanner.

Typical gurneys now found in hospitals are wheeled so they may be easilypushed around by personnel (including small women) in a hospital orclinic. The Federal Drug Administration requires that a gurney should beable to support a 350 pound patient. The table itself typically weighsapproximately 250 to 350 pounds and even with a 350 pound patient shouldbe easy to push.

A typical gurney table is seven feet long. It has been determined thatwhen designing a gurney in accordance with the present invention so thatit includes an extendable top that can extend into the central aperatureof medical imaging equipment such a CT scanner, when such a table ispositioned adjacent the medical imaging equipment, a substantial portionof the top should be able to be laterally extended, e.g. , as much asfive feet, out from the supporting base, with the remaining portion,e.g., only two feet, of the top supported over the base. The patient onthe panel is thus cantilevered relative to the table base. A particularconcern, however, is that a patient extended out into the imagingequipment may become frightened, try to push against the imagingequipment and get off the table from the cantilevered end. This couldeasily cause the table to tip and possibly injure the patient.

Accordingly, it is another object of the present invention to provide animproved system for stabilizing the relation between a patient traumatable and the medical imaging equipment.

Another object of the present invention is to provide a system forstabilizing the table relative to the imaging equipment so that evenexcessive patient load can be safely controlled under emergencyconditions.

Yet, other objects of the present invention are to provide such astabilization system in which the table can be fixed relative to theframe of the imaging equipment in order to insure that there is norelative movement between the table and imaging equipment during theimaging process, and to provide such a stabilization system wherein theposition of the table top relative to the frame can readily beascertained.

The objects of the present invention are effected generally by theprovision of a system for stabilizing a table having a top including apatient-supporting panel capable of being moved into a cantileveredposition relative to the supporting base of the table so that a portionof the panel is disposed in an imaging position with respect to medicalimaging equipment.

In the preferred embodiment of the system, the supporting table baseincludes a pair of vertically extendible devices such as screw jacks forraising, lowering and/or tilting the table top relative to the imagingequipment, the vertical extensible devices each preferably beingcontrolled by a stepper motor. The supporting table base is designed tobe attachable to the supporting structure of the imaging equipment toestablish a fixed relation between the table and the imaging equipmentthat allows substantially no relative movement between them. Astabilizing device preferably includes a support arm having a roller atone end. The support arm is preferably fixed relative to the frame ofthe imaging equipment for incremental vertical movement by a steppermotor so that the roller is movable in and out of contact with theunderside of the cantilevered end of the patient-supporting panel. Forsafety reasons, means, preferably in the form of a strain gauge, arecoupled to the support arm for providing an indication of when to stopthe stepper motor from advancing the support arm further against thetable patient-supporting panel when a predetermined roller contactpressure is exceeded. A counter is provided for counting the stepsprovided by the stepper motor driving the support arm so that theprecise position of the table top with respect to the components of theimaging equipment can be determined.

Other objects of the present invention will in part be more evident andwill in part appear hereinafter. The invention accordingly comprises theapparatus possessing the construction, combination of elements andarrangement of parts exemplified in the following detailed disclosureand the scope of the application of which will be indicated in theclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a fuller understanding of the nature and objects of the presentinvention, reference should be had to the following detailed descriptiontaken in connection with the accompanying drawings wherein:

FIG. 1 is a schematic side view of structure incorporating principles ofthe present invention and comprising a gurney coupled to medical imagingapparatus;

FIG. 2 is a schematic end view of the apparatus of FIG. 1;

FIG. 3 is a schematic side view, partially broken away, of medicalimaging apparatus of the present invention incorporating a supportmechanism in accordance with the principles of the present invention;and

FIGS. 4 and 5 are perspective views, partially broken away, showing thestabilization system of the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring now to FIGS. 1-3 there is shown medical imaging apparatus inthe form of a CT scanner. As seen in FIGS. 1 and 2, scanner preferablyincludes a yoke or cart 22 mounted on a plurality of wheels 21 so as tobe movable or portable. Cart 22 comprises a pair of preferably rigidupright sides 23 between which is supported the CT scan gantry 20.Gantry includes rigid frame 24 which rotatably supports an annulus,shown in FIG. 2 in the form of an annular disk 32, for rotation about anaxis 34. Frame 24 typically is formed as a metallic annulus or annularportion preferably of a light-weight, rigid material such as aluminum,magnesium-aluminum alloy and the like, and can be solid or hollow tominimize weight. Frame 24 is pivotally mounted on cart 22 so that theframe can be tilted about a center line or diametrical axis defined by apair of pivots 28 (shown in FIG. 2). As best seen in FIG. 2, each ofpivots 28 is fixed to frame 24 for pivotal movement therewith andextends into a corresponding bearing surface (not shown) on a respectiveone of sides 23 of the cart so that frame 24 can be pivoted about thepivot pins 28. In addition the pivot pins, and thus gantry 20, aremounted to the cart so that the entire gantry can be moved intranslation backward and forward relative to sides 23 and parallel tothe rotation axis 34. The mechanism for accomplishing the translation isnot shown in the drawings, but is described in detail in copending U.S.patent application Ser. No. 08/193,562 filed in the name of Gilbert W.McKenna and assigned to the current assignee. Frame 24 is restrainedfrom rotation in its own plane by the coupling between pivots 28 and thesides 23 of cart 22.

As best seen in FIG. 2, the annular disk 32, is rotatably mounted withinframe 24, by bearings, or preferably by suitable wheels (such asdescribed in co-pending U.S. patent application Ser. No. 08/193,783filed in the name of Gilbert W. McKenna and assigned to the currentassignee), neither of which is shown, for rotation with respect to theframe about axis 34 of rotation that extends perpendicularly throughcentral aperture 36 of disk 32. Central aperture 36 preferably isdimensioned so that the body of a patient reposed on the top of apatient table can be inserted therethrough.

An X-ray source (not shown) for defining substantially a point source ofX-rays is positioned on disk 32 in a well known manner so as to direct abeam of X-rays across aperture 36 substantially along paths disposedwithin a common plane normal to axis 34, i.e., defining the scanningplane. Similarly, in the case of third generation machines an X-raydetector array (also not shown) is mounted on disk 32, diametricallyopposite the source, so as to detect X-rays emitted by the X-ray sourceafter those rays have traversed aperture 36 along the paths of therotation plane. Other well-known components (not shown), such as a highvoltage supply for providing the necessary power to the X-ray sourceduring a scan, can be supported by the disk 32. See, for example,co-pending U.S. patent application Ser. No. 08/193,696, filed in thenames of Gilbert W. McKenna and Ronald Swain and assigned to the presentassignee. Means for driving disk 32 in rotation are also included but,in the interest of brevity are also not shown, being wholly conventionaland described in detail in, for example, U.S. Pat. No. 4,928,283. Toprotect and conceal the array of components distributed around the diskand frame of gantry 20, a skin or cover 39 (only a portion of which isshown in FIGS. 1 and 3) of an X-ray transparent material such as alight-opaque high molecular weight polymer is positioned by a pluralityof fasteners to the gantry assembly.

FIGS. 1 and 2 also show a separate, movable patient table or gurney 38modified in accordance with one aspect of the present invention. Thegurney 38 includes a supporting base generally comprising a horizontalbase member 40 supported on a plurality of wheels 42 in combination withupright support members 44 supported on base member 40 at the lower endsthereof. Members 44 serve to support at their upper extremitieselongated horizontal table top 46. In accordance with one aspect of thepresent invention, the table top 46 includes means for suspending apatient so that he or she is cantilevered relative to the base member 40in order to extend the patient into the aperture 36 of the disk. In apreferred embodiment, the means includes an elongated patient palette orpanel 48 positioned on top 46, panel 48 being slidably captured alongits long edges within two laterally extending, grooved side or railmembers 50 and 52 (seen in FIG. 2) mounted along corresponding sides oftable top 46. Means, in the form of a conventional extension driveapparatus 54 (seen in FIG. 1 ) such as a stepping motor driving a beltdevice of a known configuration and therefore only shown only in blockform, is mounted relative to top 46 and connected to panel 48 in a wellknown manner for driving the latter so that at least a portion of apatient lying on the panel can be moved relative to the base member 40in and out of aperture 36 of the gantry 20.

As best seen in FIG. 2, panel 48 is preferably formed as a transverselycurved member the side edges of which are slidably engaged by thegrooves in rail members 50 and 52, although flat panels can be used. Atleast that portion of panel 48 intended to be extendible into aperture36 is preferably X-ray transparent.

In a preferred embodiment, upright support members 44 may comprisetelescoping tubes or similar means by which the height of the foot andhead ends of table top 46 above the floor can be readily andindependently adjusted by conventional table height adjustment means 49,preferably in the form of a pair of vertically extendible devices suchas screw jacks for raising, lowering and/or tilting the table toprelative to the imaging equipment, as shown in FIG. 1 in block formonly. Such table height adjustment means facilitates positioning apatient at the center of the tomography apparatus, as seen in FIG. 1wherein the dotted lines indicate the extension of panel 48 intoaperture 36, and in FIG. 2 where the dotted outline within aperture 36illustrates the position of panel 48 when table top 46 is in an elevatedand extended (cantilevered) position.

As seen in FIG. 1, table base 40 is designed to be fixed relative to thegantry 20, and particularly to cart 22 which supports frame 24 and disk32 so as to establish a releasably fixed relation between gurney 38 andgantry 20 so as to prevent relative longitudinal movement between them.To this end, mounted at one end of table base 40 and on the base of cart22 at matching heights above floor level are respective mating parts ofa positive-locking, quick-release mechanism or latch 55 of a well knowntype, such as any of the several devices described and shown by N. PChironis, Mechanisms and Mechanical Devices Handbook, McGraw Hill, Inc(1991), pp. 400-409.

As best seen in FIGS. 1, 3, 4 and 5, the present invention also includesmeans, generally indicated at 60, for supporting and stabilizing theportion of panel 48 when table base 40 and cart 22 are releasably lockedtogether and that portion of panel 48 is extended into aperture 36. Suchsupport means is preferably provided in the form of elongated metalsupport arm assembly, generally indicated at 62. The assembly 62 isslidably fixed relative to the frame 24 (as best seen in FIG. 4), withinthe cover 39 (as shown in FIGS. 1 and 3) so that it is positioned on theside of the gantry 20 opposite the side bearing the mating portion oflatch 55 (of FIG. 1) and thus opposite the side of the gantry receivingthe panel 48.

Describing the support means 60 in greater detail, referring to FIGS. 4and 5, the support arm assembly 62 is supported by a support plate 64,which in turn is secured to the frame 24 by gussets 66 (one being shownin FIG. 4), for supporting the components of the support means 60. Theplate 64 is provided with a vertically oriented slot 68 which is longerthan the anticipated range of vertical movement of the support arm 62 aswill become more apparent hereinafter. The components of the preferredsupport arm assembly 62 positioned in front of the support plate 64(from the perspective of FIGS. 4 and 5) are illustrated in FIG. 4, whilethose components positioned behind the support plate are shown in FIG.5.

Referring to FIG. 4, a support arm assembly 62 is mounted for verticalmovement relative to the support plate 64, and thus the frame 24. Thesupport arm assembly 62 includes a frame 70 comprising at least a pairof parallel, bent arms 72, a bottom portion of which extends verticallyfor supporting the vertical panel 74 therebetween, and a top portion ofwhich extends at an angle to the vertical for supporting the diagonalpanel 76. A pair of blocks 78 are secured to the back of the verticalpanel 74 so as to be disposed between the panel and the support plate.The blocks are provided with slots 81 which are formed to respectivelycooperate with a pair of linear ways 80, which in turn are mounted onthe front side of the support plate 64 so as to be vertically orientedand parallel to one another, so as to limit movement of the assembly toan up or down motion in the vertical direction. As seen in FIG. 4, thebottom edge of the vertical panel is provided with a vertical slot 82.

The components for moving the assembly 62 in a vertical direction areshown in FIG. 5. A ball screw 84 is supported at each end in a journal86 (only one being shown in FIG. 5). The ball screw 84 is supported sothat it is restrained from movement axially, but freely rotates aboutits longitudinal axis. A ball nut assembly, generally shown at 88,includes a finger 90 (seen in FIGS. 4 and 5) which as shown in FIG. 4extends through the slot 68 of the support plate 64 and slot 82 of thevertical panel 74 of the assembly 62 so as to support the assembly 62.As seen in FIG. 5, the ball nut assembly 88 is rotatably supported onthe ball screw 84, but is restrained from rotational movement (becausefinger 90 extends through the slot 68) to axial movement along the axisof the ball screw 84 when the ball screw is rotatably driven within thejournals 86 about its axis. The ball screw is rotatably driven by means,preferably in the form of a stepping motor 92, coupled through a beltdriven pulley system 94 to the ball screw 84 so that rotation of themotor 92 in one direction causes the ball screw 84 to rotate (within thejournals 86) in one direction and the ball nut to travel up the ballscrew pushing the support arm assembly 62 with the finger 90, whilerotation of the motor 92 in the opposite direction causes the ball screw84 to rotate in an opposite direction and the ball nut to travel downthe ball screw, lowering the support arm assembly 62 as the finger movesdown the slot 68 of the support plate 64. For safety reasons, a slipclutch 95 (seen in FIG. 5) of a well known type, is provided for thefull stroke of the ball nut assembly 88 so that the ball nut assembly 88will slip relative to the ball screw 84 should a vertical force beapplied to the support arm assembly 62 in excess of a predeterminedamount, thus, preventing injury to any person when the ball nut assemblyis being raised or lowered.

The support arm assembly 62 is dimensioned and positioned so that it ismoveable into contact with the underside of panel 48 when the latter isextended into its cantilevered position. Mounted on the upper end ofsupport arm assembly 62 are means, such as wheel or roller 96, forproviding a rolling contact between the assembly 62 and panel 48.

Referring to FIG. 1, because the floor on which gurney 38 and cart 22are located can be uneven, notwithstanding that the gurney and cart maybe connected to one another near wheels 42, panel 48 when extended maybe positioned at a different location than one might expect. Further,the weight of a patient on extended panel 48 may cause the panel tobend. Thus, as seen in FIG. 5, means, shown generally as counter 100,electrically connected to stepper motor 92, is provided for up-downcounting the steps provided by operation of stepper-motor 92, therebypermitting one to ascertain the exact position of extended panel 48relative to the frame 24 and the imaging components of gantry 20 as seenin FIG. 1. For safety reasons, stress or torque-measuring means 102shown in FIG. 4, such as a spring-scale, strain gauge, Bourdon tube orthe like is so attached and positioned with respect to the underside ofthe diagonal panel 76 so as to measure the build-up of compressivestress so that when the stress exceeds a predetermined threshold, e.g.,six psi pressure, a signal is provided to stop the operation of steppermotor 92. This is helpful when moving the roller 96 into contact withthe underside of panel 48 so as to prevent excess strain on the supportarm assembly. Similarly, if an obstruction such as a person's finger iscaught between roller 96 and panel 48 when moving the support armassembly up, stepper motor 92 will also turn off when the contactpressure reaches the threshold level. Thus, there can not be a greatamount of force applied to the person's finger thereby preventingserious harm to the person.

Manually operable controls (not shown) are preferably provided forcontrolling the direction and speed of stepper motor 92. As seen in FIG.5, suitable switches 104 (one being shown in FIG. 5) can be positionedat the two desired end positions of the ball screw 84 (e.g., adjacentjournals 86) so that the finger 90 of the assembly will not travelbeyond predetermined extreme positions. The switches 104 are suitablyconnected to the stepper motor 92 so that the motor will stop when thenut assembly 88 moves into position to close one of the switches.

In preparation for a CAT scan, cart 22 and gurney 38 would be wheeledinto position so that the components of latch 55 can be releasablylocked to one another, fixing the position of the gantry 20 and gurneyrelative to one another as best seen in FIG. 1. Table top 46 is thenelevated to the desired height for centering panel 48 with respect toaperture 36 in gantry 20. Then, panel 48, carrying a subject patientwould be slidably moved into the inner, annular aperture 36 to positionthe patient properly with respect to the gantry of the CAT scanmechanism as seen in FIG. 1. Regardless of the weight of the patient orthe relative extension of panel 48 into aperture 36, the position of theportion of panel 48 extended within aperture 36, and consequently theposition of the patient relative to the tomography apparatus, ismaintained by the support provided by the support arm assembly 62 androller 96, and the position of the panel and patient can readily beascertained by examination of the read-out from counter 100 (seen inFIG. 5). Once the patient is thus initially positioned relative to thetomography apparatus, further movement of the patient or patient tableis unnecessary with the apparatus of this invention, because gantry 20generally includes means providing controlled lateral translation of thegantry 20 along the rotation axis (as described in co-pendingapplication U.S. Ser. No. 08/193,562, mentioned above) in order toproperly position the gantry relative to the patient so as to generatethe X-ray data needed for imaging. In one embodiment of this invention,therefore, X-ray imaging is performed step-wise in conjunction withincremental, precisely measured, discrete displacements of the gantryassembly with respect to the patient, which displacements are effectedby briefly and repeatedly activating the gantry displacement system. Inan alterative embodiment, X-ray imaging can also be carried outcontinuously as a helical scan by activating the gantry displacementmechanism for gradual, continuous and precisely measured lateraldisplacement of the gantry assembly while the tomography system is inoperation.

The system thus described provides an improved patient table whichfunctions both as a gurney and a table for use with large medicalimaging equipment. The support means 60 provides stabilization of thecantilevered table during imaging.

Since certain changes may be made in the above apparatus withoutdeparting from the scope of the invention herein involved, it isintended that all matter contained in the above description or shown inthe accompanying drawings shall be interpreted in an illustrative andnot in a limiting sense.

What is claimed is:
 1. A table for supporting a patient in a reposedposition, said table comprising:a base supported on wheels; a planar topfor supporting the patient in a reposed position and supported by andcapable of being moved relative to said base so that a portion ofpatient can be cantilevered relative to the base; support means forsupporting the cantilevered portion of said planar top when said patientis cantilevered relative to said base; and means for controllably movingsaid support means into and out of supporting contact with thecantilevered portion of said planar top.
 2. In combination:a medicalimaging system for forming an internal image of a portion of a patientdisposed in an imaging position; a patient table comprising a basesupported on wheels, and a planar top for supporting the patient andcapable of being moved relative to said base so that a portion ofpatient can be cantilevered relative to the base and positioned in saidimaging position; Support means for supporting the cantilevered portionof said planar top when said patient is disposed in said imagingposition; and means for controllably moving said support means into andout of supporting contact with the cantilevered portion of said planartop.
 3. The combination according to claim 2, further including meansfor securing said table to said imaging system.
 4. The combinationaccording to claim 2, further including means for stabilizing said tablerelative to said imaging system when said planar top is cantileveredrelative to said base with said patient in said imaging position.
 5. Incombination with medical imaging equipment and a patient table having abase and an elongated, substantially planar top for supporting a patientand supported by and capable of being cantilevered relative to said baseso that a portion thereof is disposed in an imaging position withrespect to said imaging equipment, a system for stabilizing said tablewhen said table top portion is disposed in said imaging position withrespect to said imaging equipment, said system comprising:support means,fixed relative to said imaging equipment, for supporting said portion ofsaid top when the latter is disposed in said imaging position; and meansfor moving said support means into and out of supporting contact withsaid top when the latter is disposed in said imaging position.
 6. Astabilizing system as set forth in claim 5, further including means forlaterally moving said top, substantially in the plane of said top, withrespect to said base into and out of said imaging position.
 7. Astabilizing system as set forth in claim 5, further including means forvertically moving the top relative to the base substantially normally tothe plane.
 8. A stabilizing system as set forth in claim 5, wherein saidimaging equipment is an X-ray tomography system including a gantryincluding a frame and a disk mounted in the frame for rotation about arotation axis, and wherein said portion of said top extends into saidaperture when in said imaging position.
 9. A stabilizing system as setforth in claim 5, further including means for determining the contactforce between the support means and said portion of said top.
 10. Astabilizing system as set forth in claim 9, further including means forarresting said movement of said support means when said contact forceexceeds a predetermined limit.
 11. A stabilizing system as set forth inclaim 10, wherein said predetermined limit is not substantially greaterthan about 6 lbs.
 12. A stabilizing system as set forth in claim 9,wherein said means for determining said contact force comprisestransducer means for providing an output signal representative of saidcontact force.
 13. A stabilizing system as set forth in claim 12,wherein said means for arresting comprises means for controlling saidmeans for moving said support means in accordance with said outputsignal.
 14. A stabilizing system as set forth in claim 5, wherein saidsupport means includes at least one roller mounted on said support meansso as to provide rolling contact between said portion of said top andsaid support means.
 15. A stabilizing system as set forth in claim 5,wherein said means for moving said support means comprises a ball nutassembly contacting said support means and axially movable along a ballscrew, and driver means mounted on said equipment for driving said ballscrew so as to axially move said ball nut assembly.
 16. A stabilizingsystem as set forth in claim 15, wherein said drive means comprise astepping motor.
 17. A stabilizing system as set forth in claim 16,including counter means for counting each increment stepped by saidstepping motor so that the relative position of said portion of said topto said medical imaging equipment can be ascertained when said contactis established.
 18. A stabilizing system as set forth in claim 16,wherein said imaging equipment includes imaging components disposed on agantry, said system further including means for releasably locking oneend of said table to said imaging equipment to establish a fixed spatialrelation between the imaging components and said portion of said topwhen the latter is disposed in said imaging position.
 19. A stabilizingsystem as set forth in claim 5, further including drive means, mountedon said top, for moving said top into said cantilevered position.
 20. Astabilizing system as set forth in claim 19, wherein said drive meanscomprises a stepping motor.